1. Field
The present invention relates to a mandrel for spiral-winding an electrode of a rechargeable battery.
2. Description of the Related Art
With the development of IT technology, various mobile devices such as smart phones and tablet personal computers (PC) are rapidly released to the market. To improve design and convenience, such devices have become increasingly thinner. In these thinner devices, battery thickness precision is important.
A rechargeable battery, such as a lithium secondary battery, typically includes a pair of electrode plates that are wound (i.e., an electrode assembly) and an electrolyte inside a case. In a rechargeable battery, repeated charge and discharge of the battery may cause swelling inside the battery, wherein the thickness of the battery increases. This swelling may be caused by the generation of a lithium compound within the battery, which can result in growth of an electrode/electrolyte interface layer. If a gap between the electrode plates in the lithium secondary battery is too small, when the electrode expands, the electrode plate may unevenly deform.
Further, when the gap between the electrode plates is too small, the side of the electrode plate may bend, resulting in a non-uniform thickness of the electrode assembly. A battery having a relatively large width and a relatively small thickness has recently been developed. However, in a battery having a small thickness, there is not a sufficient buffer space between electrodes, making it difficult to form or maintain a uniform thickness.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.